Machine tool



Nov. 1, 1966 PARRELLA ET AL 3,281,995

MACHINE TOOL Filed Dec. 20, 1963 1 5 Sheets-Sheet l HHved T. POWYO\ GeneR. Gaqhardi RMM De w ATTORNEY5 Nov. 1, 1966 Filed -Dec. 20, 1963 A- T.PARRELLA ET AL MACHINE TOOL 5 Sheets-Sheet 2 ENCODER COMPH RHTOR(B\-D\RECTIONF\L COUNTER) NUMBER TO FREQUENCY CONVERTER ENCODER DIG] THLTO PINQLOG CONVE RTER M H NUFH.

CONTROL HMPLIFlER INVENTORS Hlfied T Pavvdm Gene R Coaqharch RM M31 De wATTORNEYS 1956 A. T. PARRELLA ET AL 3,281,995

MACHINE TOOL Filed Dec. 20, 1963 5 Sheets-Sheet 5 HLTERNRTING CURRENT/96 SOURCE LMJ P113 72 m BOWDISCRIMINHTOR DlSCRlMINRTOR, 9! l lCOMPHRHTOR 95 HMPLIFIER 95 l l 4 MnNum. Z/ INVENTORS MOTOR CONTROL HhvedT. PoweHQ 3| Gene R Gaqhavch RM Ma De'iw ATTORNEY5 United States Patent3,281,995 MACHINE TOOL Alfred T. Parrella, Newtown, and Gene R.Gagliardi,

Bethany, Conn, assignors to Farrel Corporation, Ansonia, Conn.

Filed Dec. 20, 1963, Ser. No. 332,018 17 Claims. (Cl. 51-165) Thisinvention relates to machine tools and relates more particularly tomachine tools having means for aligning a longitudinally extendingworkpiece with respect to a reference axis of the machine.

The invention may be employed to advantage in roll grinding machines andwill, therefore, be dis-closed with reference to such a machine. A rollgrinder in which this invention may be embodied is disclosed in US.Patent No. 3,088,250.

Over a period of time mill rolls used in steel mills for rolling steelwill wear beyond permissible operating limits. This wear necessitatesthe regrinding of these rolls to provide the rolls with the surfacecharacteristics necessary for proper operation of the rolls in steelmills. When a roll requires regrinding, it may be placed on a grindingmachine such as that shown and described in the aforementioned patentwith the axis of the roll substantially in parallelism with a referenceaxis of the machine, which reference axis is parallel to the path oftravel of the grinding wheel of the machine. In practice it is seldom,if ever, possible to initially position a roll in the grinding machinein such a manner that its axis is within the desired degree ofparallelism with a reference axis and the path of travel of the grindingwheel. The difiiculty in positioning a roll within the desired degree ofparallelism is often due to uneven wear of the roll journals withrespect to each other. This difficulty may also be due to the rolljournal supports of the grinding machine not being properly positionedto align the axis of the roll with the path of travel of the grindingwheel.

This invention provides a new and improved machine of the characterdescribed which detects the center of each roll journal and thehorizontal distance of each journal center with respect to a referenceaxis and actuates drive means to move one end of the roll together withthe journal support in a direction and a sufficient distance so thatthere is no difference in the detected distances of the journal centersfrom the reference axis.

The invention provides new and improved means incorporated in a rollgrinder, for example, adapted to be operatively positioned with respectto each roll journal to detect the center thereof, simultaneouslymeasure the distance of each roll center from a reference axis, andprovide an indication of any difference in such distances. Theindication of such differences may be visually observed and correctiveaction initiated manually, or automatic means may be provided which isresponsive to the detected error and operative to correct such error.

Accordingly, it is an object of this invention to provide a new andimproved apparatus for detecting misalignment of a longitudinallyextending workpiece with respect to a reference axis.

Another object of this invention is to provide a new and improved meansin a roll grinding machine which detects misalignment of a roll thereonwith respect to a reference axis, and is further effective to correctsuch misalignment.

A further object of this invention is to provide new and improved meansfor detecting the center of a cylindrical object and yielding anindication indicative of the distance of the detected center from areference axis.

The features of the invention which are believed to be novel are pointedout with particularity and distinctly claimed in the concluding portionof this specification.

3,281,995 Patented Nov. 1, 1966 However, the invention both as to itsorganization and operation together with further objects and advantagesthereof may best be appreciated by reference to the following detaileddescription -taken in conjunction with the drawings, in which:

FIG. 1 is plan view of a roll grinding machine which incorporates theinvention;

FIG. 2 is a front elevation of machine in FIG. 1;

FIG. 3 is an end view of the illustration of FIGS. 1 and 2 as viewedfrom the right side;

FIG. 4 is a view similar to FIG. 3, but with certain parts shown insection;

FIG. 5 is a sectional view seen along line 5-5 of FIG. 4;

FIG. 6 is a view siimlar to FIG. 4 in illustrating roll jounal centerdetecting means, but illustrating an alternate embodiment thereof;

FIG. 7 is a diagram in block form of electrical measuring means fordetecting differences in distance of the roll axis with respect to areference axis, and prime mover means for aligning said axis;

FIG. 8 is a view similar to FIG. 4, which illustrates another embodimentof the invention; and

FIG. 9 is a diagram, partly schematic and partly in block form ofelectrical means for detecting and correcting misalignment of a rollaxis using the measuring device shown in FIG. 6.

The invention may be embodied in a roll grinder generally indicated bythe reference numeral 10 comprising a bed or frame 11 having thereonways 12 and 13, in turn having mounted thereon a grinding assembly 14movable in either direction along the ways. The grinding assembly 14includes a grinding wheel 15 adapted to operate upon a mill roll 16.Roll 16 is supported at each end thereof at journals 17 and 18 onjournal or neck supports 19 and 20, respectively.

Roll 16 is adapted to be turned on supports 19 and 20 by a drive motor21 through suitable gearing means 22. Journal 18 of roll 16 is suitablychucked to a head stock 23.

Means are provided on journal support 19 to move roll neck or journal 17towards or away from grinding wheel 15 to properly align the axis of theroll with respect to the path of travel of grinding wheel 15.

Journal 17 is mounted on support 19 by means of bearings 25 and 26 (FIG.3). Bearing 25 is mounted in the main body 27 of support 19 and bearing26 is carried in an arm 28 pivotally mounted to body 27, as indicated at29. Roll support body 27 is positionable along bed 30 on ways. Arm 28 ispivotal with respect to body 27 to allow adjustment of bearing 26 in ahorizontal direction as viewed in FIGS. 3 and 4 and thereby allowhorizontal adjustment of the axis of .roll 16.

Power drive means are provided to predetermine the position of arm 28.The drive means comprises a motor 31, carried on body 27, which drives agear 32 through a pinion 33 on the motor shaft. Gear 32 drives a leadscrew 34. Rotation of lead screw 34 produces upward or downward movementof nut 36 thereon dependent upon the direction of rotation of motor 31.Movement of nut 36 operates link 37. Link 37 is keyed to and operates torotate eccentric shaft 38. Carried on shaft 38 is a pair of links 39(only one shown) which are pivoted at the other end thereof to arm 28 at41. Rotation of eccentric shaft 38 will produce rotative motion of arm28 about ivot 29. This rotative motion of arm 28 causes neck supportbearing 26 mounted in arm 28 to move inwardly or outwardly with respectto grinding wheel 15 to move journal 17 toward or away from the grindingwheel 15.

Extending upwardly from the body 27 of each journal support is anupright member 43 which comprises oppositely disposed wall portions 44and 45 extending above journal 17 a suficient distance for the purposeshereinafter described. Wall portions 44 and 45 fixedly carrytherebetween a shaft rotative means such as a fluid motor 47 secured toa cylindrical object center-detecting assembly 48. Assembly 48 comprisesa member 49 having secured thereto fluid motor 47 to allow pivotalmovement of assembly 48 about the axis of shaft 46. Mounted in andextending from member 49 are parallel guide shafts 50 and 51 whichslidably carry thereon a member 52 on bearing means 53. Member 52carries a centering device which comprises a generally symmetricalU-shaped member 55 having roller probes 56 and 57 at either end there ofadapted to contact the surface of a cylindrical object, here shown asjournal 17. Member 55 is vertically movable with respect to member 52 bymeans of a stem 58 slidably mounted in bearing means 59 carried bymember 52. Biasing means shown as a spring 61 is provided between member52 and member 55 to normally urge member 55 downwardly towardsengagement with a cylindrical object.

Mounted in arm portion 63 of member 52 is a ball nut and screw assembly64 comprising a nut 64a and screw thread 64b on shaft 65. Antifrictionbearing elements in the form of balls are provided between the matingthreads of the nut and screw to essentially eliminate frictiontherebetween. Shaft 65 is rotatably mounted in bearing means 66 on armportion 67 of member 49 and coupled at 68 to the shaft of an encoder 69carried on member 49 at 70.

With the construction disclosed, it may be seen that as member 52 moveson guide rods 50 and 51, nut 64 will -have linear movement with respectto screw 64b and by .virtue of the ball connection therebetween suchlinear movement of nut 64a will produce rotation of shaft 65proportional to the linear movement of nut 64a.

In the device shown in FIGS. 4 and 5, the roller probes 56 and 57 aresymmetrically disposed on either side of the vetical center line ofmember 55, which coincides with the axis of stem 58. Therefore, whenboth of roller probes 56 and 57 are seated on the cylindrical surface ofjournal 17, the axes of the rollers are radially equidistant from thecenter of journal 17 and form equal angles with the center line throughstem 58. At this time the center line of stem 58, which is the verticalcenter line of member 55 passes through the center of journal 17. Thetravel of member 52 on guide rods 50 and 51 to properly seat probes 56and 57 is a measure of the horizontal distance between the axis of shaft46 and the center of journal 17. As hereinafter described,-the motion orrotation of shaft 65 is used to properly align the axis of roll 16 withrespect to the axis of travel of grinding wheel 15. Stop ping means isprovided in the form of a lug 43a on member 43 to engage the undersurface of member 49, as viewed in FIG. 3, to maintain assembly 48 andguide rods 50 and 51 horizontal when assembly 48 is rotated intooperative position from the position show in broken line (FIG. 4).

FIGS. 3 and 4 illustrate a center locating device wherein the locationof the center is signalled by rotation of shaft- 65. Shaft encoders'which produce a digital or pulse output proportional to rotation of ashaft are well known to those skilled in the art and may be utilized inthe present invention as hereinafter described.

FIG. 6 illustrates an alternate embodiment of the invention wherein thelongitudinal movement of a member 50 is detected by a linear variabledifferential transformer 72. As well known to those skilled in the art,and hereinatfer exemplified in FIG. 9, a linear variable differentialtransformer is a transformer designed with two secondaries that are soarranged that at some position of a movable core, the output from eachindividual secondary is of equal amplitude and phase relation. The secondary windings are connected in series opposition so that the outputscancel. The secondary windings are distributed in such a manner that anyphysical displacement of the core causes the voltage in one secondary toincrease while simultaneously reducing the voltage in the othersecondary. The difference between the two voltages appears across theoutput terminals of the serially opposed secondaries and gives a measureof the physical position of the core. By detecting the magnitude of theoutput and the phase difference between the primary excitation voltageand the output voltage, linear movement of the core is detected. Suchmotion transducers are available from many sources, one of which isDaytronic Corporation of Dayton, Ohio, whose model 102B-160 linearvariable differential transformer has been satisfactorily utilized in astructure exemplified in FIG. 6.

In utilizing the apparatus as shown in FIG. 4 a roll to be ground isfirst placed on the journal supports 19 and 20 and a centering assembly48 on each of the journal supports is pivoted about its respective shaft46 from the position shown in broken line in FIG. 4 to a positionsimilar to that shown in full line in FIG. 4. It will be understood thatinitially member 52 is at its furthest degree of travel to the left asviewed in FIGS. 4 and 5. Then member 55 is urged downwardly towardsjournal 17 under the bias of spring 61 and roller probes 56 and 57 willseek the lowest possible location on journal 17. This lowest possiblelocation occurs when both roller probes 56 and 57 have their axesequidistant from the center of roll 16. To assume such a position ofmember 55 it is necessary for member 52 to move to the right, as viewedin FIGS. 4 and'S, causing nut 64a to move along screw 64b. This in turnproduces rotation of screw 64b in shaft 65 proportional to the lineardistance travelled by nut 64. Rotation of shaft 65 in a preferred formof the invention causes encoder 69 to produce a plurality of pulsesproportional in number to the linear movement of member 52. Therefore,the pulse output of encoder 69 is indicative of the horizontal distancebetween the axis of shaft 46 and the center of journal 17 In a similarmanner, apparatus like that shown in FIGS. 4 and 5 is carried on rollsupport 20 and will yield the same information.

It will be understood that the axes of the shafts 46 on both of thejournal supports coincide and such coincident axis is parallel to thepath of travel of grinding wheel 15 along ways 12 and 13. Therefore, anydifference in the outputs of shaft encoder 69 on journal support 17 orshaft encoder 69', FIG; on journal 18 is indicative of the deviation inthe axis of roll 16 with respect to the path of travel of grinding wheel15. Such difference may be detected in a number of ways known to thoseskilled in the art. One exemplary way is to apply the pulse output ofboth of the shaft encoders to a comparator 75 (FIG. 7) in the form of abidirectional counter to determine the difference. The error thenappears as the resultant number in the counter. This number in thecounter is then converted to a pulse frequency by number-to-frequencyconverter 76 and subsequently converted to a voltage by adigital-to-analogue converter 77. The votlage may then be read on avisual-indicating meter and the operator manually operates motor 31 tomove journal 17 toward or away from grinding wheel 15 until the axis ofroll 16 is parallel to the line of travel of grinding Wheel 15 and alsothe axis defined by shafts 46. At such time the visual-indicating meter78 would show zero error. Alternatively, the number in the comparator 75might be read directly by a suitable read-out means. In anotheralternative, the motor 31 may be automatically operated through anamplifier 79 which is sensitive to both the magnitude and the directionof the error. In this last mentioned arrangement the axis of the roll 16would be automatically aligned with the reference axis. Automatic ormanual control systems for eliminating any difference in the distance ofthe center of each journal from a reference point are known to thoseskilled in the art and various other systems and electrical componentsmay be utilized.

It is to be understood that journal support 20, not illustrated indetail, supports journal 18 in a similar manner to that shown forjournal 17. However, it is not necessary to provide means, such as arm28, to move journal 18 toward and away from grinding wheel 15.

In the embodiment of the invention shown in FIGS. 4 and 5 the assembly48 may be arranged to be pivoted about the pin 46 by means of the fluidmotor 47. In another embodiment of the invention the center-detectingand signalling means are arranged to be raised and lowered by means suchas a hydraulic cylinder. As exemplified in FIG. 8 a center-detectingmeans 80 and an indicating means, again in the form of a shaft encoder81, are carried on an arm 82 which is mounted to a shaft 83 rotatablycarried by a journal support member 84. Shaft 83 has a gear 85 thereondrivably engaged by a worm 86 driven by a motor 87, also mounted onjournal support 84. The motor 88 is effective to rotate arm 82 on shaft83 to aid in positioning centering assembly 80 011 roll journal 88. Thecentering assembly is movable vertically by means of a cylinder 89 whichcomprises arm 82.

In operation, the center-detecting means 80, together with theindicating means, is moved in a vertical direction towards or away fromthe roll journal 88 by means of cylinder 89 and when thecenter-detecting assembly and indicating means are not required motor 87may be energized to move this assembly from the roll journal to aposition as shown in broken line.

In FIG. 8 it may be seen that the structure of the detecting means 80varies slightly from the structure of the detecting means shown in FIGS.4 and 5. Likewise, the encoder carrier of FIG. 8 differs slightly fromthat of FIGS. 3, 4 and 5. However, the construction and operation of theapparatus of FIG. 8 will be apparent from the foregoing descriptions.

FIG. 9 illustrates another electrical measuring system using linearvariable differential transformers 72 and 72' to measure the distancesof the journal centers from a reference axis. Here the measureddistances as detected in discriminators 90 and 91 are compared in acomparator 92. The resultant error may be visually indicated on a meter93 and a manual motor control 94 actuated to operated motor 31.Alternatively, an amplifier 95 may be utilized to sense the directionand magnitude of the error and operate motor 31 to nullify the measurederror and thereby align the roll axis with respect to a reference axis.The discriminators 90 and 91 compare the magnitudes and phases of theprimary voltage of alternating current source 96 with the magnitudes andphases of the secondary votlages of transformers 72' and 72,respectively. The discriminators 9t and 91 then yield a signalindicative of movement of cores 72a and 722) respectively.

It may thus be seen that the objects of the invention set forth, as wellas those made apparent from the preceding description are etficientlyattained. Other embodiments of the invention as well as modifications tothe disclosed embodiments of the invention may occur to those skilled inthe art for practicing the invention. Accordingly, it is intended tocover in the appended claims all embodiments and modifications of theinvention which do not depart from the spirit and scope of theinvention.

What is claimed is:

1. In a machine tool of the type wherein a workpiece having generallycylindrical surfaces is supported at either end thereof and arranged tobe axially aligned with a reference axis, the improvement comprising;means for detecting the center of a workpiece adjacent either endthereof, support means including guide means, said detecting means beingmovable on said guide means in a direction substantially perpendicularto the axis of a workpiece whose center is to be detected, and meansresponsive to movement of each of said detecting means for indicatingthe distances of the detected centers from a reference axis.

2. In a machine tool of the type wherein a workpiece having generallycylindrical surfaces is supported at either end thereof and arranged tobe axially aligned with a reference axis, the improvement comprising;means the object until the difference is zero.

3. In a roll grinder of the type wherein a mill roll is supported onjournal ends thereof on journal supports and arranged to be axiallyaligned with a reference axis, the improvement comprising; means fordetecting the center of each journal at its journal support, supportmeans including guide means, said detecting means being movable on saidguide means in a direction substantially perpendicular to the axis of amill roll supported on the grinder, and means responsive to movement ofeach of said detecting means for indicating the distance of the detectedcenters from a reference axis.

4. The apparatus of claim 3 further including means for moving one ofthe journal supports to eliminate any difference in the distance of thedetected centers from the reference axis.

5. The apparatus of claim 3 including means for comparing the distancesof the detected centers from the reference axis and means responsive tosaid comparing means for moving one of the journal supports toessentially eliminate the difference.

6. In a machine tool of the type wherein a workpiece having cylindricalsurfaces is supported at either end thereof and arranged to be axiallyaligned with a reference axis and wherein means are provided forsupporting the workpiece adjacent either end thereof, the improvementcomprising; means for detecting the center of the workpiece adjacenteither end thereof, means actuated by each of said detecting means forindicating the distance of the detected centers from a reference axis,means responsive to each of said indicating means for deriving arepresentation of the difference in the distance of the detected centersfrom the reference axis, and means responsive to the representation formoving one of the supports until the difference in the distance of thedetected centers from the reference axis is zero.

7. A device for detecting the center of a cylindrical object comprisinga member movable perpendicular to a reference axis, said member carryingthereon probe members arranged to engage a cylindrical surface onopposite sides of the center of the cylindrical surface, said probemembers being symmetrically disposed with respect to a vertical centerline and movable in a second direction perpendicular to the referenceaxis so that when said probes contact the cylindrical surface thevertical center line passes through the center of the cylindricalsurface, and means for detecting the first perpendicular movement ofsaid member to seat said probes on the cylindrical surface.

8. In a machine tool of the type wherein a workpiece is supported ateither end thereof and arranged to be axially aligned with a referenceaxis and wherein means are provided for supporting the workpieceadjacent either end thereof, the improvement comprising; means fordetecting the center of the workpiece adjacent either end thereof, meansactuated by said detecting means for indicating the distance of thedetected centers from a reference axis and means responsive to saidindicating means for deriving a representation of the difference in thedis-.

tance of the detected centers from the reference axis.

9. The apparatus of claim 8 wherein said means for detecting comprises amember movable horizontally perpendicular to the reference axis, saidmember having thereon probe members arranged to engage a cylindricalsurface, said probe members being symmetrically disposed with respect toa vertical center line so that when said probes contact the cylindricalsurface the vertical center line passes through the center of thecylindrical surface.

10. The apparatus of claim 9 wherein said means for detecting ispivotally mounted on the machine tool for movement toward and away fromthe cylindrical surface.

11. In a roll grinder of the type wherein a mill roll is supported onjournal ends thereof on journal supports and arranged to be axiallyaligned with a reference axis and wherein means are provided forsupporting the workpiece adjacent either end thereof, the improvementcomprising; first and second means for detecting the center of eachjournal, each of said means for detecting being pivotally mounted on thegrinder about a common axis and each adjacent a journal so that saidmeans for detecting may be pivoted into or away from engagement with anassociated journal to allow a roll to be placed on and removed from thesupport, each of said detecing means being linearly movablesubstantially perpendicular to the axis of a mill roll to locate thecenter thereof, and means responsive to movement of each of saiddetecting means from a reference line to indicate the distance of saiddetecting means from said reference line.

12. The apparatus of claim 11 wherein said means for detecting comprisesa member movable horizontally and perpendicular to the reference axis,said member having thereon probe members arranged to engage acylindrical surface, said probe members being symmetrically disposed'with respect to a vertical center line so that when said probes contactthe cylindrical surface the vertical center line passes through the axisof the cylindrical surface.

13. A device for detecting the axis of a cylindrical object comprisingmeans for supporting a cylindrical object, a probe member havingdepending probe arms symmetrically disposed on either side of a centerline, said arms being adapted to engage the peripheral surface of acylindrical object, a probe carrying member, a mounting member carriedon said means for supporting a cylindrical object, guide means carriedby said mounting member, said probe carrying member being movable onsaid guide means, biasing means interposed between said probe member andsaid probe carrying member urging said probe member away from said probecarrying member and toward an object whose center is to be detected sothat when one of said probe arms contacts a cylindrical object, saidbiasing means acts to urge both said arms into engagement with theobject on either side of the axis thereof and equidistant therefrom andsaid mounting member is moved on said guide means.

14. A device for detecting the axis of a cylindrical object comprisingmeans for supporting a cylindrical object, a probe member havingdepending probe arms symmetrically disposed on either side of a centerline, said arms being adapted to engage the peripheral surface of acylindrical object, a probe carrying member, a mounting member carriedon said means for supporting a cylindrical object, guide means carriedby said mounting member, said probe carrying member being movable onsaid guide means, biasing means interposed between said probe member andsaid probe carrying member urging said probe member away from said probecarrying member and toward an object whose center is to be detected sothat when one of said probe arms contacts a cylindrical object, saidbiasing means acts to urge both said arms into engagement with theobject on either side of the axis thereof and equidistant therefrom andsaid mounting member is moved on said guide means, and means 8' formeasuring the position of said probe means with respect tov a referenceline.

15. A device for detecting the axis of a cylindrical object comprisingmeans for supporting a cylindrical object, a probe member havingdepending probe arms symmetrically disposed on either side of a centerline, said arms being adapted to engage the peripheral surface of acylindrical object, a probe carrying member, a mounting member carriedon said means for supporting a cylindrical object and including guidemeans, said probe carrying member being movable on said guide means,biasing means interposed between said probe member and said probecarrying member urging said probe member away from said probe carryingmember and toward an object whose center is to be detected so that whenone of said probe arms contacts a cylindrical object, said biasing meansacts to urge both said arms into engagement with the object on eitherside of the axis thereof and equidistant therefrom and said mountingmember is moved on said guide means, said mounting member beingpivotally mounted to saidmeans for supporting a cylindrical object.

16. A device for detecting the axis of a cylindrical object comprisingmeans for supporting a cylindrical object, a probe member havingdepending probe arms symmetrically disposed on either side of a centerline, said arms being adapted to engage the peripheral surface of acylindrical object, a probe carrying member, guide means carried by saidmeans for supporting a cylindrical object, said probe carrying memberbeing movable on said guide means, biasing means interposed between saidprobe member and said probe carrying member urging said probe memberaway from said probe carrying member and toward an object whose centeris to be detected so that when one of said probe arms contacts acylindrical object said biasing means acts to urge both said arms intoengagement with' the object on either side of the axis thereof andequidistant therefrom, and said mounting member is moved on said guidemeans.

17. An element having probe arms symmetrically disposed on either sideof a center line, said arms being adapted to engage the peripheralsurface of a cylindrical object, a support member for said element,means biasing 'said element away from said support member so that saidprobe arms may contact the peripheral surface of a cylindrical objectand tend to seat themselves equally on either side of the axis thereof,mounting means, said mounting means including guide means, said supportmember being freely movable on said guide means in a directionsubstantially perpendicular to the direction of movement of said probemember by said biasing means.

References Cited by the Examiner UNITED STATES PATENTS 1,808,392 6/ 1931Waldrich 5149 2,312,161 2/1943 Hartman 5149 2,544,156 3/1951 Hathaway51-98 X 2,864,211 12/1958 Balsiger et a1. 51289 3,056,243 10/1962Flanders 51-289 3,070,925 1/ 1963 Woodford et al 5149 FOREIGN PATENTS476,363 12/1937 Great Britain.

LESTER M. SWINGLE, Primary Examiner.

3. IN A ROLL GRINDER OF THE TYPE WHEREIN A MILL ROLL IS SUPPORTED ONJOURNAL ENDS THEREOF ON JOURNAL SUPPORTS AND ARRANGED TO BE AXIALLYALIGNED WITH A REFERENCE AXIS, THE IMPROVEMENT COMPRISING; MEANS FORDETECTING THE CENTER OF EACH JOURNAL AT ITS JOURNAL SUPPORT, SUPPORTMEANS INCLUDING GUIDE MEANS, SAID DETECTING MEANS BEING MOVABLE ON SAIDGUIDE MEANS IN A DIRECTION SUBSTANTIALLY PERPENDICULAR TO THE AXIS OF AMILL ROLL SUPPORTED ON THE GRINDER, AND MEANS RESPONSIVE TO MOVEMENT OFEACH OF SAID DETECTING MEANS FOR INDICATING THE DISTANCE OF THE DETECTEDCENTERS FROM A REFERENCE AXIS.